Circuit-interrupting system



Dec. 28 1926.

H. A. TRAVERS ET AL CIRCUIT INTERRUPTING SYSTEM Filed Feb. 4. 1921 INVENTORS Henry/1 Tmrrr: 8. Ckaliar McL. Mos:

' ATTORNEY WITNESSES:

motive force.

Patented Dec. 28, 1926.

v UNITED STATES PATENT OFFICE.

HENRY A. TRAVERS, OF FOREST HILLS BOROUGH, AND CHARLES McL. MOSS, F PITTS- BUBGH, PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANU- FACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CIROUIT-INTERRUPTING SYSTEM.

Application filed February 4, 1921.

Our invention relates to circuit interrupting systems and particularly to remotely controlled circuit interrupters.

One object of our invention is to prevent vide a master switch for controlling the closing circuits of a' plurality of interrupters in an electrical system to render the closing circuits ofthe several interrupters ineffective, after the automatic tripping of one interrupter, until the master switch may be reset.

Another object of our invention is to provide a system, of the above indicated character, in which only one control switch shall be required to effect the protection of a pluralityof circuit interrupters by preventing any one of the interrupters from being held closed while a heavy overload or short-cirpjuit obtains on the circuit controlled there- A further object of our invention is to provide a system of the above indicated character that shall be simple and inexpensive in construction, and efi'ective in its operation.

Electrically operated circuit interrupters are usually closed by an electromagnetic mechanism, such, for example, as a motor or an electromagnet, the moving member of e which is operatively connected to the movable member of the circuit interrupter. The circuit interrupter is usually latched in its closed position and, to open the same, the latch must be released or tripped by means of a trip coil.

A remotely-disposed control switch, that is ordinarily manually operated, is used to connect the coils of the closing or tripping mechanism to a suitable source of electro- If the control switch is actuated to cause the circuit interrupter to close while an overload or short circuit obtains on the circuit, overload relays, thatv are provided for the protection of the circuit under such conditions, may complete a circuit to the trip coil and cause it to release Serial No. 442,418.

the control switch, the circuit interrupter is held closed through the closing mechanism.

In view of the conditions just stated, we provide a master switch for automatically opening the circuit that includes the coil or coils of the closing mechanism, thus preventing the circuit interrupter from being held closed upon a short circuit or heavy overload, if abnormal conditions obtain when the control switch is actuated to close the circuit interrupter.

The master switch is so arranged that the circuit of the coil for energizing the closing mechanism cannot be re-established until the master switch has been reset. The resetting of the master switch may be eliected either by a remote-control, push-button switch convenient to the attendant or by the control switch of any circuit interrupter.

It is necessary that the circuit of the closing coil be opened and maintained so until the attendant resets the master switch, since, otherwise, the circuit of the closing coil would be re-established and the circuit interrupter would close and open again and would continue this so-called pumping action so long as the control switch should be maintained in its closed position.

This continual closing and opening of the circuit interrupter on a heavy overload or short circuit might considerably damage the apparatus connected to the circuit and would subject the interrupter mechanism to unnecessary and heavy stresses and the contacts to the danger of fusing.

The single figure of the accompanying drawing is a diagrammatic view of a circuit interrupting system embodying our invention.

A bus circuit 1 is provided with energy from a source 2 of electromotive force and supplies energy to a plurality of feeder circuits 3 and 4: through individual circuit interrupters 5 and6.

The interrupter 5 comprises an operating mechanism 7, a closing coil 8 for operating the mechanism 7 to close the interrupter and a trip coil 9 for opening the interrupter 5. The interrupter 5 is further provided with an auxiliary switch 10 comprising a plurality of contacts 11 that are engaged by a bridging member 12 when the interrupter 5 is closed and a plurality of contacts 13 that when lighted, indicates that the interrupter is in its closed position, while the green lamp 18, when lighted, indicates thatthe interrupter is in its open position.

The circuit 3 is provided with a plurality of current transformers 20 and 21 that energize a plurality of overload relays 22 and 23 in accordance with the current traversing the circuit 3.

The relays 22 and 23, preferably of the induction-type having an inverse time-element, are each provided with apair of contact members 24, engagement of which is effected when the relay becomes energized beyond a predetermined degree for a predetermined interval of time.

The circuit interrupter 6 is similarly provided with an operating mechanism '25, a closing coil 26, a trip coil 27 and an auxiliary switch 28, the bridging member 29 of which engages a plurality of contact members 30, when the interrupter is closed, and a plurality of contact members 31 when the interrupter is open.

The control switch 32 for controlling the interrupter, 6 comprises a closing switch 33 and a'trip switch 34. The trip switch 34 controls the circuit of the trip coil 27 and also of the master relay to be mentioned later.

The control switch 32 is further provided with a red lamp 35 and a green lamp 36 which operate, as mentioned above, to indicate the position of the interrupter 6.

The circuit 4 is provided with a plurality of current transformers 40 and-41 that energize a plurality of relays 42 and 43, respectively. The relays'are each provided with a pair of contact members 44.

Energy for operating the control mecha- 1 nism of the interrupters is obtained from a control circuit 50. The closing switch 15, when operated, completes a circuit from the positive conductor 51, through the closing coil 8 of the interrupter 5, to a common bus conductor 52 which is connected to the negative conductor 53 of the control circuit by a switch 55 of the master relay 55.

The master relay 55 comprises the switch 55 that is normally closed and a switch 56 that is normally open. When the master relay 55 is actuated, the switch 56 becomes closed and the switch 55. is opened. The relay 55 further comprises a pivoted member 57 a latching member 58 that serves to 61 acting 'upon the latch member 58 against the tension of a spring 62 to effect the release of thepivoted member 57.

The operating coil 61 of the relay 55 is connected between the positive conductor 51 of the control circuit and a common relay bus conductor 54 that is connected to one contact member of each of the overload relays 22, 23, 42 and 43. The reset. coil 60 is connected between the negative conductor 53 of the control circuit 50 and the positive conductor 51 either through a push button switch 65 or through a common reset bus conductor 70 and either of the trip switches 16 or 34.

The interrupter 5 is closed by depressing the switch 15 to complete a circuit from the positive conductor 51 through the switch 15, the closing coil 8, the bus conductor 52 and the switch 55 of the master relay 55 to the negative conductor of the control circuit.

If, while the switch 15 is depressed and maintainedin that position, a short circuit should obtain at the point"A on the circuit 3, the current transformers 20 and 21 would energize the relays 22 and 23 to effect the engagement of the contact members 24.

Upon the engagement of those contact members, a circuit would be completed from the negative conductor 53 of the control circuit, through the contact members 11 and the bridging member 12 of the auxiliary switch 10, the trip coil 9, the contact members 24 of the relays 22 and 23, the bus conductor 54 and the operating coil 61 of the master relay 55, to the positive conductor 51 of the control circuit. 7

The trip coil 9 of the interrupter be energized and themaster relay, 55 would be operated to close its switch56 and to open its switch 55 The opening of the switch 55 opens the circuit of the closing coil 8, thereby de-energizing that coil and permitting the trip coil 9, which is still energized, to trip the interrupter 5. The

interrupter 5 is thus precluded from being held closed, upon a. heavy overload or short circuit, as at the point A, by the operation of the master relay 55, which operates the switch 55 to open the circuit of the closing coil 8.

The master relay 55 may be reset either by the switch 65, which may be remotelydisposed with respect to the relay 55, and convenient to theat'tendant, or by-the trip switch 16, which will also complete the circuit for energizing the reset coil 60. The

, 110. 5 would master relay 55 may thus be reset by the attendant while he is at the switch board operating the control switch 14 or, when faulty conditions occur on the system, while it is operating, that would effect the automatic tripping of any interrupter and the simultaneous operation of the relay 55, at which time he might be away from the switch board.

The operation of the red and green lamps to indicate the positions of the corresponding interrupters is controlled by the auxiliary switches of the corresponding interrupters. The operation ofthe auxiliary switch 10 serves to connect the trip coil 9 in parallel with either the red or the green lamp, depending upon whether the interrupter is in its open or its closed position. For example, if the interrupter is open, the trip coil 9 is connected in parallel with the red lamp and the combined circuits of the two in series with the green lamp. Thus, only the green lamp is sufficiently energized to produce incandescence, since the resistance of the trip coil 9 is Sufliciently less than that of either lamp to deflect a greater portion of the current from the lamp.

The operation of the control apparatus employed with the interrupter 6 is similar to that described above in connection with the interrupter 5.

The master relay 55, by connecting .or disconnecting the control switches of the several interrupters and the control circuit 50, is enabled to control the operation of a plurality of interrupters for feeder circuits to preclude them from being held closed on a short circuit.

Our invention is not limited to the specific arrangement, as illustrated, since various modifications may be made therein within the spirit and scope of the invention, as set forth in the appended claims.

We claim as our invention 1. The combination with a plurality of circuit interrupters, a plurality of circuits controlled thereby a closing coil and a trip coil for each of the circuit interrupters and a source of energy for energizing the coils, of a latching device for controlling the operation of the circuit interrupters comprising a coil for actuating the device to its latched position, a coil for unlatching the device, means for energizing said unlatching coil in response to a predetermined condition in the said controlled circuits, and a switch that is closed when the device is latched, said switch being connected between the source of energy and the closing coils of all of the circuit interrupters.

2. In an electrical system. the combination with a plurality of feeder circuits and individual circuit interrupters therefor having a closing coil and a trip coil, and overload relays for energizing the trip coil upon the occurrence of a predetermined overload upon the respective circuits, of a single means actuated upon the operation of the relays of one feeder circuit for rendering ineffective the closing-coil-energizing means of all the feeder circuits.

3. The combination with a plurality of circuit interrupters, a closing coil and a tripcoil for each of the circuit interrupters, a source of energy for energizing the coils, and an overload relay associated with'each circuit interrupter and having a switch connected in series with the trip coil of the associated circuit interrupter of a latching device for controlling the operation of the circuit interrupters comprising a coil for actuating the device to its latched position, a coil for unlatcliing the device, and a switch that is closed when the device is latched; said unlatching coil being so connected that current traversing the trip coil of any of the circuit interrupters, by reason of the closing of the switch of the associated overload relay, must also traverse the unlatching coil in series therewith; and said switch of the latching device being connected between the source of energy and the closing coils of all of the circuit interrupters.

4. In an electrical s stem, the combination with a plurality o circuit interrupters, adapted to be tripped automatically upon the occurrence of predetermined abnormal conditions, individual power-operated means for closing each interrupter and a source of energy therefor, of individual devices through which energy must pass to energize the corresponding power-operated device and a common device through which the energy must pass in series with the individual devices, said common device being actuated upon the automatic tripping of one interrupter to disconnect the individual devices from the source of energy until said common device is reset.

5. In combination, a plurality of feedercircuit conductors, individual circuit interrupters therefor, a magnet for closing the movable members of the interrupters, means for tripping the movable member, individual switches for closing the circuits through the coils of the magnets of the respective interrupters, and a common switch included in the circuits of the coils of all of the cl osing magnets and opened upon the occurrence of predetermined abnormal conditions in one feeder circuit.

6. The combination with a plurality of circuit interrupters, a closing coil and a trip coil for each of the circuit interrupters, a source of energy for energizing the coils, a manually operable switch associated with each circuit interrupter for energizing the trip coil thereof, and an overload relay associated with each circuit interrupter and havcoil of the associated circuit interrupter, of a latching device for controlling the operation of the circuit interrupters comprising a coil for actuating the device to its latched position, a coil for unlatching the device and a switch that is closed when the device is latched; said latching coil being so connected that it is energized whenever the manually operable tripping switch of any of the circuit interrupters is closed; said unlatching coil being so connected that current traversing the trip coil ofany of the circuit interrupters,'by reason of the closing of the.

switch of the associated overload relay, must also traverse the unlatching coil in series therewith; and said switch of the latching device being connected between the source of energy and the closing coils of all of the circuit interrupters.

In testimony whereof, we have hereunto subscribed our names this 28th day of J anuary, 1921.

HENRY A. TRAVERS. CHARLES MoL. MOSS. 

